Control device



Feb. 26, 1 52 c. G. KRONMILLER CONTROL DEVICE 2 SHEETS-SHEET 1 FiledSept. 2. 1949 INVEN TOR. (7 6- XFdNM/LLEE Feb. 26, 1952 c. G. KRONMILLERCONTROL DEVICE 2 SHEETSSHEET 2 Filed Sept. 2, 1949 INVENTOR. 64.84 GIK/EONM/LLEE 172550 rneg Patented Feb. 26, 1952 UNITED STATES PATENTOFFICE CONTROL DEVICE Carl G. Kronmiller, Edina, Minn., assignor toMinneapolis-Honeywell Minneapolis, Minn., a corporation of DelawareApplication September 2, 1949, Serial No. 113,884

9 Claims. 1

This invention is directed to a control point adjusting means applicableto thermostats and other condition controlling devices.

An object of the invention is to provide a control device havingadjusting mechanism including a pair of manually positionable cams, oneof which adjusts the control point and the other of which positions apointer with respect to suitable indicia to indicate the selectedcontrol point.

Another object is to provide a control device having a knob that may bemanually rotated to adjust and indicate the control point and that maybe moved axially to actuate a switch controlling a light bulb disposedto illuminate the indicia of condition value.

.Other objects will be evident from the following description andclaims, and fromthe drawing, in which ,Figure 1 is an elevation of aroom thermostat embodying the invention, the cover being re-. 'moved andcertain parts broken away for the sake of clarity,

Figure 2 is a fragmentary section taken on line 2-2 of Figure 4 showingdetails of the cam adjusting mechanism,

Figure 3 is a fragmentary section taken on line 3-3 of Figure 4 showingdetails of the connection between the cam structure and the rod thatpositions it,

Figure 4 is an elevation taken in section along line 44 of Figure 1, thecover also being shown in section, a

Figure 5 is a rear elevation of the device of Figure 1, and

Figure 6 is a diagrammatic view showing an electrical circuit in whichthe'thermostat may be used.

While the invention is applicable to various control devices, it isillustrated in connection with a thermostat adapted to control thesupply of heat to a room. The thermostat has a base ID of suitableinsulating material such as molded Bakelite, the back surface beingrecessed as at H to receive a wall plate (not shown) to which connectingwires may be secured and to which the thermostat itself is secured byits terminal screws in a manner well known in the art. A bracket I2 issecured to the front surface of the base ID by screws l3 and M, thescrew l3 extending through the base to electrically connect the'bracket|2 to a conducting strip |5 shown in Figure 5. The strip |5 carries aterminal screw Hi, the slotted head of which is accessible from thefront of the base through a hole therein.

The bracket |2 has an outwardly extending portion |2a at its right handend which carries a Regulator Company,

spring blade 20. A switch arm 2| is secured to the blade 28 adjacent thebracket portion l2a, the intervening portion of the blade 20 serving'asa spring hinge for the switch arm. A movable contact 22 is mounted onthe right hand end of the blade 20 and is biased with respect to theswitch arm 2| by the blade 20 to provide a limited amount of press backas disclosed in my copending application Serial No. 681,461, filed July5, 1946, now Patent No. 2,493,294, dated January 3, 1950.

Another bracket 25 is secured to the front surface of the base In at thelower right hand corner by screws 26 and 21, the screw 26 extendingthrough the base to form an electrical connection with a conductingstrip 28 on the rear surface thereof. A terminal screw 29 is held on thebase IE] by the strip 28 and an opening is provided in the base and inbracket 25 to permit access to the screw head. A contact screw 30, theupper end of which is adapted to cooperate with movable contact 22, isadjustably carried in the bracket 25. The bracket 25 also carries apermanent magnet 3| which cooperates with the switch arm 2| to causesnap action of contact 22 into and out of engagement with stationarycontacts, the switch arm 2| being made of suitable magnetic material toact as an armature for the magnet 3|.

A pivot pin 34 is mounted on th left hand end of bracket l2 and extendsoutwardly therefrom normal to the base ID. A member 35 having ahorizontally disposed bimetal element 36 secured thereto is pivotallymounted on the pin 34, the member 35 having an extension 35a the righthand end of which carries a calibrating screw 38 which engages anadjusting'cam to be hereinafter described. The right hand end of thebimetal element 36 passes through an opening in a very thin strip Mlwhich is secured to the extremity of the switch arm 2|. As seen inFigure 4 the strip 40 has a very narrow portion intermediate the bimetal36 and switch arm 2| to render the connection very flexible. Thisconnection between the switch arm and the bimetal element isinstrumental in providing a clean snap action of the switch contactsince the strip 4|! flexes sufiiciently during the snap action toprevent sliding action between the strip and the bimetal element.

An anticipating heater 43 is secured to bimetal element 35 by a screw 44which passes through an insulating washer 45, a conducting washer 46,and is screw threaded into the member 35. Heater 43 is preferably ofcylindrical form and is made of a suitable carbon or graphitecomposition to provide the desired resistance. A pigtail connection 48connects the washer 45 with a screw 49 that extends through the base Hito form an electrical connection with a conducting strip 50 on the backof the base. A terminal screw 5| is carried in the base it by the strip55.

A molded plastic cam shaft 55 has a reduced cylindrical end portion 55that is journaled in the base 15, as is shown in Figure l. The outer endof the cam shaft 54 is also provided with a.

cylindrical bearing portion 55 journaled in a bracket 58, the majorportion of which is spaced which also cooperates with the indicia onthe;

scale plate 66 to indicate existing temperature. The scale plate 52 i isprovided with a slot 6'! that serves as a guide for a pointer t8 whichcooperates with the indicia to indicate'the adjusted temperature atwhich contacts 22-30 will be engaged to call for heat. Thepointer G8 is.provided with a .rearwardly extending pin lfi'which. is connected by alink it? to a pin "M. extending A cam 82, molded integrally withtheparallel to the pin it from a lever '55 which is.v

pivoted on a pin 3'5 in the bracket 55." 12 comprises an upperrelatively rigid member 7211. which is formed at either end to engagepins 10..andjl l, and a lower springstrip 72?) which. holds the pinsinengagement.withnpperportion 12a... This constructionpermits readyassembly.

of the pointer 58 onscale plate 64 andalso prevents. lost motion,between the pointer. and the.,

lever 78. Thelower end of. the lever 1511s,. U..-

shaped. and the rear leg forms. a cam follower.

85 which is biased by a spring (li-intoengager.

ment with a cam that is molded integrally It will benoted thatas. thecam shaft 54 is rotated to adjust cam. 52,.

with the cam shaft 5%.

and hence the bimctal elements, to determine the control point of thethermostat, cam. 52 is, also positioned to adjust lever itandthenceuthe,

pointer 68'to indicate the control point. Thebir metal supporting memberis biasedby a spring;

83 in a clockwise direction to assurepositivaen;

gagement of the calibrating screw. with the.

The action of spring makesit more difiicult to adjust the cam 52. in.

surface of the cam. 52.

a counterclockwise direction than in a clockwise direction. On the otherhand, spring E5! biases the cam follower. 550 against the cam 82 (whichis oppositely disposed h respect to the cam 62) making it more difficultto adjust the cam 82 in a clockwise direction than in a counterclockwisedirection. The combined effect of the springs 83} and tlion the camshaft 5:?- results in there being very little difference-in the forcerequired to rotate it in the opposite direction.

Scale plate 64 isformedof a translucent material and is adapted to beilluminated by a light.

bulb 85 having a conducting; base 85 secured in place on the base it bya strip 8'! which grasps the base 88, extends along the base ill and issecured thereto by a screw 88. The screw 88 extends through the base andforms an electrical. connection with a conducting; strip 39.

The link.

The base i5 and strip 89 are provided with openings through which thehead of a terminal screw 99 is accessible. A conducting strip 92 ofresilient material is secured to the rear side of the base as seen. inFigure 5 by a pair of rivets 93 which also secure a strip of insulatingmaterial in overlyingrelation withrespect to the conducting strip 92. Anextension 92a :ofithe strip 92 extends outwardly through an opening inbase ill to engage the center terminal connection of the light bulb 85.The lower end 5212 of the strip SZextends through an opening in the insulating .strip fi l and overlies its lower extremity.Thestripportion92b' is disposed to lie underneath but spaced .fcm anextension a of the conducting strip which carries the terminal screw'5i.

The strip portion 92b is normally out of engagement with the conductingstrip 50 but may be forced into engagement therewith by a pin 96 thatextends axially through the base I 0, the. The outer, end oi the pin 925carries an adjusting knob 98by cam shaft 5 1, and the bracket 58.

means of which the pin 96 can be rotatedand strip 5i cooperate to formaswitch in theglight bulb circuit extending from the terminal screw;- 98.throughthe strip. 87, the light bulb 85and through the. strips 92'.and.5fl-. to the. terminal: screw 5 i.

As best seen in Figure 3 thepin .96 is laterally v bored to receive apin I00 which has a force fit therein. Pin lilfl extends laterallythrough a-slot in the inner end of the cam shaft 54. The pin I00 keysthe pin'96 to-the cam shaft 54 so-that rotational movement of theknob 98will be-im parted to the cam shaft 54 but axial movement" of the knob 98and the pin 96 will be'perrnitted with respect to the cam shaft toactuate the switch 92b-50a.

As seen in Figure 4 a cover-"I02 is securedfto the base Ill and enclosesthe base and all ofthe described mechanism with-theexception of outer;

portion of the knob 98 which extendsthrqugh a suitable opening therein.A transparent wing dow I03 is providedin the cover IUZadJ'acent theindicia on the scale plate 64, the thermometer tube andthe pointer 68..

Under conditions of normal illumination in the room in which thethermostat is installed'the knob 98 may be rotated to adjust.control'point of the instrument and to indicate it on scale plate 64.However, there aremany times when it is. desirable, as. when retiringat. night, to, ad:

just the thermostat without turning. on, general;v room illumination.Under these conditions thev thermostat may be adjusted bypushing inonthe; knobflil to energize the light bulb while; ro-

tating the knob 98 to select thedesired tempera-1 ture. It. is alsopossible, of course, tov employ. this light. source to merely check theadjusted.

positionof the pointer 68 or to read the ther-\ mometer.

One possible electrical circuit in which this thermostat may be employedis-shownin Figure-- 6. A transformer I05 havinga lowvoltage secm ondarywinding I06 may serve as. a source of The thermostat may be'used'electrical current. to control any commonload llllsuchasa solenoidgasvalve, oil burner-relay or the like. The

main control; circuit extends; from theitranseformer secondary I06through a wire I08 to the load I01 and through a wire I09 to theterminal screw I6. Current is conducted through the bracket I2, switcharm 2|, contacts 2230, and the bracket 25 to the terminal screw 29, andthence through a wire IIO to the opposite side of the transformersecondary I08. It will be evident that the load I! will be energizedwhenever the thermostat contacts are closed. The left hand connection ofthe transformer secondary I06 is connected to the terminal screw 5| by awire III which energizes the anticipating heater 43 through the pig-tail48. The opposite connection to the heater 43 is through the bimetalelement and through the member 35 and pin 34 to the bracket I2 which isconnected to the opposite side of the transformer secondary whenever thethermostat contacts are closed. Thus heater 43 will be energizedwhenever the thermostat calls for heat and the heater 43 will supplyadditional heat to the bimetal element to cause the thermostat contactsto open after an interval of time whether heat is actually supplied tothe room or not. When the knob 98 is pushed inwardly the switch 50a-92bwill be closed and a circuit will be completed to the light bulb 85 fromthe terminal screw 5| through conducting strips 50 and 92 to the lightbulb 85. Conducting strip 81 connects the base of the light bulb 85through the terminal screw 90 and a wire I I3 to the terminal screw 29.

While the invention has been described in connection with a roomthermostat adapted to control a heating system it will be evident tothose skilled in the art that it could be equall well applied to acooling thermostat or for that matter to any other condition controllingdevice, for example, a room humidostat. Likewise, the in- 3. In acontrol device, a base, a thermostat on said base, a first cam foradjusting the control vention is applicable to any control device whereit is desirable to adjust the control point and indicate it at the sametime. Many modifications of the invention will be apparent to thoseskilled in the art and I am therefore to be limited only by the appendedclaims.

I claim as my invention:

1. In a thermostat, a base adapted for mounting on the wall of a room, athermostatic element pivotally mounted on said base, a switch actuatedby said thermostatic element, a cam for pivotally positioning saidthermostatic element to determine the temperature at which said switchis actuated, a plate carrying indicia of temperature and a pointermovable with respect ihereto, a lever pivoted in said base forposit1oning said pointer with respect to said indicia, a cam forpositioning said lever and means for rotating simultaneously both ofsaid cams, said pointer indicating the temperature at which saidthermostatic element actuates said switch.

2. In a thermostat, a base adapted for mounting on the wall of a room, athermostatic element pivotally mounted on said base, a switch actuatedby said thermostatic element, a cam for pivotally positioning saidthermostatic element to determine the temperature at which said switchis actuated, a plate carrying indicia of temperature rectilinearlydisposed thereon and a pointer movable rectilinearly with respectthereto, a lever pivoted in said base for positioning said pointer withrespect to said indicia, a

link interconnecting said lever and said pointer,

point of said thermostat, a temperature indicator carried by said base,a second cam for adjusting said indicator, a light bulb for illuminatingsaid indicator, a switch controlling the circuit for said bulb, andmanually operable means including a member extending through both ofsaid cams for rotating said cams, said member also being axiallyslidable in said cams to actuate said switch.

4. In a control device, a base, condition responsive means and controlmeans carried on said base, cam means for relatively positioning saidmeans to adjust the condition value at which said control means isactuated by said condition responsive means, an indicator comprising apointer and indicia of condition value, a linkage interconnecting saidcam means and said indicator for causing said indicator to show thecondition value at which said control means will be actuated, a lampbulb disposed to illuminate said indicia and said pointer, a switchcontrolling energization of said lamp bulb, and manually positionablemeans rotatable coaxially with said cam to adjust the control means andslidable axially with respect thereto to actuate said switch.

5. In a control device, a base, a member pivoted in said base, a bimetalelement attached to said member, a switch actuated by said bimetalelement, an indicator comprising a relatively movable pointer andindicia of temperature, a lever pivoted in said base and a connectionbetween said lever and said indicator, cam-means pivoted in said baseand engaging said member and said lever, a knob. rotatable to adjustsimultaneously said bimetal and said indicator, a light bulb disposedfor illuminating said indicator, and a switch in control of said lightbulb, said switch actuated by axial movement of said knob.

6. In a control device, a base, a member pivoted in said base, a bimetalelement attached to said member, a switch actuated by said bimetalelement, an indicator comprising a relatively movable pointer andindicia of temperature, a lever pivoted in said base and a connectionbetween said lever and said indicator, cam means pivoted in said baseand engaging said member and said lever, manually positionable meansincluding a rod extending axially through said cam means and keyedthereto, a light bulb disposed to illuminate said indicator, and aswitch in series circuit with said light bulb, said rod extendingthrough said base to actuate said light switch on axial movement of saidmanually positionable means with respect to said cam means.

7. In a control device, a base, a thermostatic element and a switch onsaid base, a bracket on said base having a portion parallel to said basebut separated therefrom, a scale plate carried by said bracket, apointer movable with respect to said scale plate to indicate thetemperature at which said element will actuate said switch, a campivotally mounted between said base and said bracket portion andconfined thereby against axial movement, connections between said camand said element and between said cam and said pointer, a rod disposedcoaxially of said cam and having a knob at its outer end, meansinterconnecting said rod and said cam causing concurrent ivotal movementthereof but permitting relative axial movement therebetween, a lightbulb adapted to illuminate said scale plate and pointer, and a switch incircuit with said light 7 nlbiaacfiuat i; he, nner n of 1 a 99 axiaimnvment hereon,

imsaidbase for, positioning said pointer with re,-v

spectto said indicia; a link interconnecting said 1eyer and saidpointer, acam for positioning saidg lever, and means for rotatingsimultaneously -both of-saidcams, said pointer indicating the em r te-at i h.saidt e m a m n etu es i sw h:

9-, lmacontrol device, a base, a thermostat on said, base, a unitary camstructure pivotally mountedon saidbase andhaving first and sec- 0ndspiral earn surfaceswith-their effective sur-u faces ing ite dir c ionshrwe muip ed t rmine an pi n ul r movement. againfollower connected tosaid thermostat engaging said first cam surface,- an indicator, a camfol;

lower connected to said indicator engaging said secondcam surface, andmeans biasing each of said cam? followers into engagement with said:

cam surfaces.

CARLHG. K O M -LER.

REFERENCES CITED The following references areof record in the file ofthis patent;

UNITED STATES PATENTS um am M:v

1,639,618 h r "r'ft'ffffr't"? 1,711,931 Farrington May 7, 1929 2,051,181Saar Aug. '18; 1936' 2,124,089 Stuerzl July 19,1933; 2 2 ,3 ickmeya J e,9. 2 2 2? i ma nei at O t. .950

